219 - Effect of Co-Medications and Endotoxins on Mesenchymal Stem Cell Characteristics

Abstract

The impact of immunosuppressive medications and endotoxemia on mesenchymal stem cell (MSC) therapy have not been established. We examined the effects of calcineurin inhibitors cyclosporin (Cyc) & tacrolimus (Tac), corticosteroids hydrocortisone (Hyd) & dexamethasone (Dex), rapamycin (Rap), mycophenolic acid (MPA) and lipopolysaccharide (LPS) endotoxins on bone marrow MSC secretion of cytokines and growth factors that contribute to MSC activation, anti-inflammatory and regenerative functions. We used Luminex bead platform to assess expression of 41 cytokines (Table 1). We showed secretion of cytokines that activate MSC such as IFNγ and TNFα was increased in response to all compounds tested. However, other cytokines with similar effect such as IL-1α and IL-17 were largely unaffected. Factors known to play a role in MSC-induced immunosuppression and cell differentiation such as IL-10, EGF and TGFα were variably affected. LPS and Dex increased secretion of IL-10, while effects of other medications were concentration dependent. TGFα secretion was increased by LPS and MPA with variable effects induced by other drugs. EGF secretion was largely decreased, yet was increased by MPA and Tac at high concentration. We evaluated changes in secretion of factors known to induce angiogenesis, neurogenesis, hematopoiesis and epithelial proliferation such as VEGF, IL-6, GM-CSF and G-CSF. LPS, Tac, and Cyc exposure increased secretion of VEGF-A. Contrarily, corticosteroids and Rap (except 1 ng/ml) decreased VEGF-A secretion. IL-6 secretion was increased by LPS, Rap, Tac and Cyc and decreased by MPA and corticosteroids. With few exceptions, LPS increased and immunosuppressive drugs decreased GM-CSF secretion. G-CSF was increased by LPS, but unaffected by the drugs evaluated. In summary, MSC characteristics are influenced by immunosuppressive medications and endotoxins. Further studies are necessary to evaluate how these variations might affect the intended therapeutic function of MSC. Table 1(a) Drugs and LPS were added to BM-MSC culture medium in three concentrations. Analyte concentrations after 72 hours in culture were compared with concentrations in the control wells containing 0.2% DMSO only. Increases over the control concentration are denoted in red, decreases are denoted in green and white indicates there was no change in analyte concentration between the control and experiment. (b) Red boxes indicate that all three drug/LPS dilutions tested resulted in an increase in analyte concentration. Green boxes indicate that all dilutions produced a decrease in analyte concentration. White boxes indicate that there is variability among the three concentrations as to whether an increase, decrease or no change was observed.